Peebles Audio Engineering calibration tapes are available here: https://www.naks.es/

Naks are far from the only cassette decks with these types of adjustments. Sony, Aiwa, Technics, Teac, Kenwwod all make terrific three head decks with all these same adjustments for 1/4 the price. Fan boys be fan boys.

I happened to see this video of yours and found it very entertaining as well as educational… I avoided Nakamaichi’s due to reputation that they are hard to work on and very expensive. Plus I’m a big fan of all things Dolby S TOTL 3 head cassette decks. So in 2012 when I came back to tapes after about 20 years hiatus. Started getting my hands on Aiwa xk-s 7000,9000. Sony tc-ka5es, pioneer ct-93, t1000s, etc etc.  When COVID hit, I took a chance got my first Nakamichi, RX-505 and wow I was blown away and could flip that tape all day long 😂. Now in 3 years I have 12 Nakamichi’s the CR7A,CR4A,CR3A. ZX-9, 682ZX, 680,660ZX,BX-300 which is my favorite cause of the bass bump! MR-1B, last acquired items: RX-202 and of course the Dragon… So I became  Nak convert but still love all things Dolby S as well… Keep continuing your videos I’ve learn a lot..

Some small notes to add:
Adjusting bias is not a "more is better/higher level" thing. Bias results in a bell curve of the high frequency response. You'll notice quite quickly that there is a peak and on either side of the peak (lower or higher bias) the 15Khz tone will rapidly drop in amplitude. So don't be tempted to just keep adding bias to increase high frequency level, the opposite will happen.
Classic transport 3 head Naks to watch for:
LX-5, ZX-7, ZX-9, 670, 680, Dragon, 700 Mark II, 1000 Mark II, RX-505
3 head Naks to AVOID (no tape monitoring):
660, 581, 582 has tape monitoring but feels like a Fisher Price toy.
There's a long standing myth perpetrated by Nak haters that Nakamichi uses a non-standard equalization. This is false, and it's been around so long that Nakamichi published an official rebuttal with tech data in the 1970s. The myth originated from their competitors slagging them off and trying to convince people that the reason Nak decks sounded better was because they were somehow cheating.

Wonderful,
Can't believe more "viewers"  haven't "liked" this video.
Keep up the great work
Alun

Teac V7000 has these adjustment pots for levels too on both bias and levels they also have individual heads as Naks they use the same or similar  transport systems

Incredibly useful, thorough and informative! Thank you!!! 👍👍👍

Thanks for this clear demonstration. To save some space you can buy (not expensive) the NAK T-100  audio analyzer software. It has a generator and scope. Works fine for me.

The best video i’ve seen so far this year 🙏

I finally pulled the trigger and bought a CR3 I had been stalking because of this video, thank you! (Also reached out to Peebles about the calibration tapes as I only have a 3k speed calibration tape in my collection, double thank you)

Very nice Video, always learning something new. Keep up the good Work!

I did measurements by NAK T-100 of bias for tapes like basf, jvc, maxell, orwo, agfa, durateaoe, sony , denon, tdk of all kinds: metal, CrO2, ferro and normal. Write the results on the paper, and now I can adjust my deck to any specific tape. Nice!

Excellent, thanks!

Outstanding! This has got to be high in the running for best video on the tube.

Thanks. Very informative!

I though height was the in/out horizontal movement of the head, not the twisting zenith motion you indicated?  Although that does alter the height of the middlemost part of the head i agree.

Incredible video !!! I have the Nakamichi 581 and I was pissed when I found out I couldn’t monitor the third head . Yes the 582 does Grrrrrrrrrrr😢😢

Immediately recognized the analog watch and thought this guy is old school.
LOL
Great video...subscribed.
I own 2 Nakamichi's...You know why.

Great video - thanks

You rock Sir!